sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

alb_break_llc() decides whether to break LLC preference during active
load balance. It does so by testing that every runnable fair task on the
source rq prefers its LLC:

	env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable

But the two counters cover different sets. nr_pref_llc_running is updated
in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued,
so it follows queued tasks. h_nr_runnable is updated in set_delayed()/
clear_delayed() and drops delay-dequeued tasks.

So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted
in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks,
alb_break_llc() returns false, and active balance is free to pull a task
off its preferred LLC. Active balance only moves runnable tasks, and this
is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB
skips the per-task test in can_migrate_task(). The runnable set is the one
we want.

Fix it on the counter side. A task should be counted in
nr_pref_llc_running exactly while it is both queued on its preferred LLC
(pref_llc_queued) and runnable (!sched_delayed). Define that membership
once in task_pref_llc_runnable(), and adjust the counter only through
pref_llc_running_inc()/pref_llc_running_dec() from the four sites that
change either input: account_llc_enqueue(), account_llc_dequeue(),
set_delayed() and clear_delayed(). Gating every update on the same
predicate keeps the delay, wake and dequeue paths from double-counting
or underflowing; see the comments at those sites for the ordering.

nr_llc_running and sd->llc_counts are not touched and stay on queued
semantics.

Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC")
Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/
Reported-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 464 insertions, 0 deletions

diff --git a/crypto/authencesn.c b/crypto/authencesn.c
new file mode 100644
index 000000000..ca063576f
--- /dev/null
+++ b/crypto/authencesn.c
@@ -0,0 +1,464 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
+ *                 derived from authenc.c
+ *
+ * Copyright (C) 2010 secunet Security Networks AG
+ * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
+ * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <crypto/internal/aead.h>
+#include <crypto/internal/hash.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/authenc.h>
+#include <crypto/scatterwalk.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+struct authenc_esn_instance_ctx {
+	struct crypto_ahash_spawn auth;
+	struct crypto_skcipher_spawn enc;
+};
+
+struct crypto_authenc_esn_ctx {
+	unsigned int reqoff;
+	struct crypto_ahash *auth;
+	struct crypto_skcipher *enc;
+};
+
+struct authenc_esn_request_ctx {
+	struct scatterlist src[2];
+	struct scatterlist dst[2];
+	char tail[];
+};
+
+static void authenc_esn_request_complete(struct aead_request *req, int err)
+{
+	if (err != -EINPROGRESS)
+		aead_request_complete(req, err);
+}
+
+static int crypto_authenc_esn_setauthsize(struct crypto_aead *authenc_esn,
+					  unsigned int authsize)
+{
+	if (authsize > 0 && authsize < 4)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
+				     unsigned int keylen)
+{
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
+	struct crypto_ahash *auth = ctx->auth;
+	struct crypto_skcipher *enc = ctx->enc;
+	struct crypto_authenc_keys keys;
+	int err = -EINVAL;
+
+	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
+		goto out;
+
+	crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
+	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
+				     CRYPTO_TFM_REQ_MASK);
+	err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
+	if (err)
+		goto out;
+
+	crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
+	crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc_esn) &
+					 CRYPTO_TFM_REQ_MASK);
+	err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
+out:
+	memzero_explicit(&keys, sizeof(keys));
+	return err;
+}
+
+static int crypto_authenc_esn_genicv_tail(struct aead_request *req,
+					  unsigned int flags)
+{
+	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
+	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
+	u8 *hash = areq_ctx->tail;
+	unsigned int authsize = crypto_aead_authsize(authenc_esn);
+	unsigned int assoclen = req->assoclen;
+	unsigned int cryptlen = req->cryptlen;
+	struct scatterlist *dst = req->dst;
+	u32 tmp[2];
+
+	/* Move high-order bits of sequence number back. */
+	memcpy_from_sglist(tmp, dst, 4, 4);
+	memcpy_from_sglist(tmp + 1, dst, assoclen + cryptlen, 4);
+	memcpy_to_sglist(dst, 0, tmp, 8);
+
+	memcpy_to_sglist(dst, assoclen + cryptlen, hash, authsize);
+	return 0;
+}
+
+static void authenc_esn_geniv_ahash_done(void *data, int err)
+{
+	struct aead_request *req = data;
+
+	err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
+	aead_request_complete(req, err);
+}
+
+static int crypto_authenc_esn_genicv(struct aead_request *req,
+				     unsigned int flags)
+{
+	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
+	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
+	struct crypto_ahash *auth = ctx->auth;
+	u8 *hash = areq_ctx->tail;
+	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
+	unsigned int authsize = crypto_aead_authsize(authenc_esn);
+	unsigned int assoclen = req->assoclen;
+	unsigned int cryptlen = req->cryptlen;
+	struct scatterlist *dst = req->dst;
+	u32 tmp[2];
+
+	if (!authsize)
+		return 0;
+
+	/* Move high-order bits of sequence number to the end. */
+	memcpy_from_sglist(tmp, dst, 0, 8);
+	memcpy_to_sglist(dst, 4, tmp, 4);
+	memcpy_to_sglist(dst, assoclen + cryptlen, tmp + 1, 4);
+
+	sg_init_table(areq_ctx->dst, 2);
+	dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+
+	ahash_request_set_tfm(ahreq, auth);
+	ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
+	ahash_request_set_callback(ahreq, flags,
+				   authenc_esn_geniv_ahash_done, req);
+
+	return crypto_ahash_digest(ahreq) ?:
+	       crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
+}
+
+
+static void crypto_authenc_esn_encrypt_done(void *data, int err)
+{
+	struct aead_request *areq = data;
+
+	if (!err)
+		err = crypto_authenc_esn_genicv(areq, 0);
+
+	authenc_esn_request_complete(areq, err);
+}
+
+static int crypto_authenc_esn_encrypt(struct aead_request *req)
+{
+	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
+	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
+	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
+						  ctx->reqoff);
+	struct crypto_skcipher *enc = ctx->enc;
+	unsigned int assoclen = req->assoclen;
+	unsigned int cryptlen = req->cryptlen;
+	struct scatterlist *src, *dst;
+	int err;
+
+	if (assoclen < 8)
+		return -EINVAL;
+
+	sg_init_table(areq_ctx->src, 2);
+	src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
+	dst = src;
+
+	if (req->src != req->dst) {
+		memcpy_sglist(req->dst, req->src, assoclen);
+		sg_init_table(areq_ctx->dst, 2);
+		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
+	}
+
+	skcipher_request_set_tfm(skreq, enc);
+	skcipher_request_set_callback(skreq, aead_request_flags(req),
+				      crypto_authenc_esn_encrypt_done, req);
+	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
+
+	err = crypto_skcipher_encrypt(skreq);
+	if (err)
+		return err;
+
+	return crypto_authenc_esn_genicv(req, aead_request_flags(req));
+}
+
+static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
+					   unsigned int flags)
+{
+	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
+	unsigned int authsize = crypto_aead_authsize(authenc_esn);
+	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
+	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
+						  ctx->reqoff);
+	struct crypto_ahash *auth = ctx->auth;
+	u8 *ohash = areq_ctx->tail;
+	unsigned int cryptlen = req->cryptlen - authsize;
+	unsigned int assoclen = req->assoclen;
+	struct scatterlist *src = req->src;
+	struct scatterlist *dst = req->dst;
+	u8 *ihash = ohash + crypto_ahash_digestsize(auth);
+	u32 tmp[2];
+
+	if (!authsize)
+		goto decrypt;
+
+	if (src == dst) {
+		/* Move high-order bits of sequence number back. */
+		memcpy_from_sglist(tmp, dst, 4, 4);
+		memcpy_from_sglist(tmp + 1, dst, assoclen + cryptlen, 4);
+		memcpy_to_sglist(dst, 0, tmp, 8);
+	} else
+		memcpy_sglist(dst, src, assoclen);
+
+	if (crypto_memneq(ihash, ohash, authsize))
+		return -EBADMSG;
+
+decrypt:
+
+	dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
+	if (req->src == req->dst)
+		src = dst;
+	else
+		src = scatterwalk_ffwd(areq_ctx->src, src, assoclen);
+
+	skcipher_request_set_tfm(skreq, ctx->enc);
+	skcipher_request_set_callback(skreq, flags,
+				      req->base.complete, req->base.data);
+	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
+
+	return crypto_skcipher_decrypt(skreq);
+}
+
+static void authenc_esn_verify_ahash_done(void *data, int err)
+{
+	struct aead_request *req = data;
+
+	err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
+	authenc_esn_request_complete(req, err);
+}
+
+static int crypto_authenc_esn_decrypt(struct aead_request *req)
+{
+	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
+	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
+	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
+	unsigned int authsize = crypto_aead_authsize(authenc_esn);
+	struct crypto_ahash *auth = ctx->auth;
+	u8 *ohash = areq_ctx->tail;
+	unsigned int assoclen = req->assoclen;
+	unsigned int cryptlen = req->cryptlen;
+	u8 *ihash = ohash + crypto_ahash_digestsize(auth);
+	struct scatterlist *src = req->src;
+	struct scatterlist *dst = req->dst;
+	u32 tmp[2];
+	int err;
+
+	if (assoclen < 8)
+		return -EINVAL;
+
+	if (!authsize)
+		goto tail;
+
+	cryptlen -= authsize;
+	memcpy_from_sglist(ihash, req->src, assoclen + cryptlen, authsize);
+
+	/* Move high-order bits of sequence number to the end. */
+	memcpy_from_sglist(tmp, src, 0, 8);
+	if (src == dst) {
+		memcpy_to_sglist(dst, 4, tmp, 4);
+		memcpy_to_sglist(dst, assoclen + cryptlen, tmp + 1, 4);
+		dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+	} else {
+		memcpy_to_sglist(dst, 0, tmp, 4);
+		memcpy_to_sglist(dst, assoclen + cryptlen - 4, tmp + 1, 4);
+
+		src = scatterwalk_ffwd(areq_ctx->src, src, 8);
+		dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+		memcpy_sglist(dst, src, assoclen + cryptlen - 8);
+		dst = req->dst;
+	}
+
+	ahash_request_set_tfm(ahreq, auth);
+	ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
+	ahash_request_set_callback(ahreq, aead_request_flags(req),
+				   authenc_esn_verify_ahash_done, req);
+
+	err = crypto_ahash_digest(ahreq);
+	if (err)
+		return err;
+
+tail:
+	return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
+}
+
+static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
+{
+	struct aead_instance *inst = aead_alg_instance(tfm);
+	struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
+	struct crypto_ahash *auth;
+	struct crypto_skcipher *enc;
+	int err;
+
+	auth = crypto_spawn_ahash(&ictx->auth);
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
+
+	enc = crypto_spawn_skcipher(&ictx->enc);
+	err = PTR_ERR(enc);
+	if (IS_ERR(enc))
+		goto err_free_ahash;
+
+	ctx->auth = auth;
+	ctx->enc = enc;
+
+	ctx->reqoff = 2 * crypto_ahash_digestsize(auth);
+
+	crypto_aead_set_reqsize(
+		tfm,
+		sizeof(struct authenc_esn_request_ctx) +
+		ctx->reqoff +
+		max_t(unsigned int,
+		      crypto_ahash_reqsize(auth) +
+		      sizeof(struct ahash_request),
+		      sizeof(struct skcipher_request) +
+		      crypto_skcipher_reqsize(enc)));
+
+	return 0;
+
+err_free_ahash:
+	crypto_free_ahash(auth);
+	return err;
+}
+
+static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
+{
+	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
+
+	crypto_free_ahash(ctx->auth);
+	crypto_free_skcipher(ctx->enc);
+}
+
+static void crypto_authenc_esn_free(struct aead_instance *inst)
+{
+	struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
+
+	crypto_drop_skcipher(&ctx->enc);
+	crypto_drop_ahash(&ctx->auth);
+	kfree(inst);
+}
+
+static int crypto_authenc_esn_create(struct crypto_template *tmpl,
+				     struct rtattr **tb)
+{
+	u32 mask;
+	struct aead_instance *inst;
+	struct authenc_esn_instance_ctx *ctx;
+	struct skcipher_alg_common *enc;
+	struct hash_alg_common *auth;
+	struct crypto_alg *auth_base;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
+	if (err)
+		return err;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+	ctx = aead_instance_ctx(inst);
+
+	err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
+				crypto_attr_alg_name(tb[1]), 0, mask);
+	if (err)
+		goto err_free_inst;
+	auth = crypto_spawn_ahash_alg(&ctx->auth);
+	auth_base = &auth->base;
+
+	if (auth->digestsize > 0 && auth->digestsize < 4) {
+		err = -EINVAL;
+		goto err_free_inst;
+	}
+
+	err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
+				   crypto_attr_alg_name(tb[2]), 0, mask);
+	if (err)
+		goto err_free_inst;
+	enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "authencesn(%s,%s)", auth_base->cra_name,
+		     enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+
+	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "authencesn(%s,%s)", auth_base->cra_driver_name,
+		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+
+	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
+				      auth_base->cra_priority;
+	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
+	inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
+	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
+
+	inst->alg.ivsize = enc->ivsize;
+	inst->alg.chunksize = enc->chunksize;
+	inst->alg.maxauthsize = auth->digestsize;
+
+	inst->alg.init = crypto_authenc_esn_init_tfm;
+	inst->alg.exit = crypto_authenc_esn_exit_tfm;
+
+	inst->alg.setkey = crypto_authenc_esn_setkey;
+	inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
+	inst->alg.encrypt = crypto_authenc_esn_encrypt;
+	inst->alg.decrypt = crypto_authenc_esn_decrypt;
+
+	inst->free = crypto_authenc_esn_free;
+
+	err = aead_register_instance(tmpl, inst);
+	if (err) {
+err_free_inst:
+		crypto_authenc_esn_free(inst);
+	}
+	return err;
+}
+
+static struct crypto_template crypto_authenc_esn_tmpl = {
+	.name = "authencesn",
+	.create = crypto_authenc_esn_create,
+	.module = THIS_MODULE,
+};
+
+static int __init crypto_authenc_esn_module_init(void)
+{
+	return crypto_register_template(&crypto_authenc_esn_tmpl);
+}
+
+static void __exit crypto_authenc_esn_module_exit(void)
+{
+	crypto_unregister_template(&crypto_authenc_esn_tmpl);
+}
+
+module_init(crypto_authenc_esn_module_init);
+module_exit(crypto_authenc_esn_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
+MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
+MODULE_ALIAS_CRYPTO("authencesn");